Process for producing unsaturated compounds



July 16, 1968 M. J. P. BOGART PROCESS FOR PRODUCING UNSA'IURATED COMPOUNDS Filed April 15, 1965 Product S? m Geng ofor 1F- 38 Purification Unit A 5? r\ 1V V 56 Quench INVENTOR Marcel J. P. Bogart ATTORNEYS United States Patent 3,393,250 PROCESS FOR PRODUCING UNSATURATED COMPOUNDS Marcel J. P. Bogart, London, England, assignor to The Lunirnus Company, New York, N.Y., a corporation of Delaware Filed Apr. 15, 1965, Ser. No. 448,433 6 Claims. (Cl. 260-679) ABSTRACT OF THE DISCLOSURE A process for producing a desired unsaturated compound wherein a crude oil is withdrawn from a pipeline and a light fraction of the crude is subjected to pyrolysis conditions. The desired unsaturated compound is recovered from the cracked effluent and the intermediate pyrolysis fractions recycled to the pipeline. In this manner a desired unsaturated compound is selectively produced from a pipeline crude.

This invention relates to a process for producing unsaturated compounds, such as, for example, ethylene and acetylene from a crude oil which is being passed through provide an improved process for producing ethylene, aeet- V ylene and the like which is economic both in terms of capital and operating costs, and which avoids the necessity of making and disposing of various intermediate process streams.

Various other objects and advantages of the invention will become clear from the following description of an embodiment thereof, and the novel features will be particularly pointed out in connection with the appended claims.

In the process of the present invention, a quantity of crude oil is withdrawn from a pipe line and passed through a vaporizer in which a portion of the crude is vaporized With the unvaporized portion being returned to the pipe line. The vapors are then passed to cracking coils or a Wulff furnace, and the crack gas product is thereafter quenched and passed to a conventional purification unit. The heavy oils and unconverted feed stock from the quenching zone are also returned to the pipe line.

In the purification unit, the desired unsaturated compound, such as ethylene, acetylene and the like, is produced and recovered while light oils and aromatic distillates are returned to the pipe line. Ethane and light fractions such as C C and C compounds, for example, are recycled to the cracking coils and, if desired, a residue gas may also be withdrawn from the purification unit for fuel purposes within the plant.

The invention will be further illustrated by reference to the accompanying drawing, which is a flow sheet according to the invention, and in which a pipeline 2 contains a crude oil. From the pipeline 2 a portion of the crude oil is withdrawn through the line 4 and passed to a vaporizer 6 into which fuel is introduced through the line 8. The oil is vaporized to a 500 F. end point (or thereabout), and the product stream from the vaporizer is passed through the line 10 to the disengaging zone 12 in which the vaporized portions of the crude oil separate from the reduced crude. The reduced crude is returned 3,393,250 Patented July 16, 1968 "ice by means of the pump 14 and line 16 to the pipe line 2. The vaporized portion of the crude oil is passed from the disengaging zone 12 through the line 18 to furnaces 20, which are designated in the flow sheet as Wultf furnaces.

One skilled in the art will realize that the operating temperatures, etc., maintained in furnace 20 will be varied to suit a particular crude being treated and also to maximize production of desired products. Further, the pressure of operation will also have an effect on operation, whether it be atmospheric, vacuum type operation or pressurized.

In a preferred embodiment of the invention, however, the vaporized oil is cracked at a temperature of 1600 to 1900 F. at a pressure of about 17 to 20 p.s.i.a. For a particular crude, 1700 F. and 18 p.s.i.a. were preferred. The product of the cracking coils is passed through line 22 to the quenching zone 24, where the reaction products are quickly cooled to below the temperature at which further reaction and undesired secondary reactions can take place (around 1000 F.).

The crack gas from the quenching zone 24 is passed through the line to a conventional purification unit 32 from which a product ethylene stream is withdrawn through the line 34. If desired, a product acetylene stream may also be simultaneously withdrawn from the purification unit 32. A fraction comprising ethane and light hydrocarbons such as C C and C compounds, is withdrawn from the purification unit through the line 36 for recycle to the cracking coils or furnaces 20. Residue gas is withdrawn from the purification unit through the line 38 and passed through the line 40 to the cracking coils to provide fuel therefor and residue gas .is also passed through the line 42 as fuel to the steam generator 44.

High pressure steam is withdrawn through the line 46 from the steam generator and passed to the purification unit. Boiler feed water is introduced into the steam generator through the line 48. Low pressure steam is withdrawn from the steam generator through the line 50 and passed to the furnaces or cracking coils 20.

Light oils and aromatic distillates are withdrawn from the purification unit through the line 52 and passed by means of the pump 54 and line 56 to the pipe line 2.

Thus, from the foregoing, it is apparent that the process of the present invention provides a simple means for producing one unsaturated product from a pipe line stream with return of all intermediate fractions to the pipe line. The process may be adapted to the removal from the pipe line stream of any of a number of desired unsaturated compounds but is primarily applicable to the production of ethylene and/ or acetylene.

It will be obvious to those skilled in the art that many modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications, as defined in the appended claims.

What is claimed is:

l. A process for producing an unsaturated compound which comprises withdrawing a crude oil from a pipe line, passing the oil to a vaporization zone in which a portion of the oil is vaporized, cracking the vaporized portion in a cracking zone, quenching the product stream from the cracking zone, passing the quenched cracked gas to a purification zone wherein a light fraction, a product stream and intermediate fraction are separated, recycling the light fraction from the purification zone to the cracking zone, recovering the product stream containing the desired unsaturate from the purification unit as a product of the process, and returning the intermediate fractions to the pipe line downstream of the withdrawal point.

2. A process according to claim 1, wherein a residue gas is recovered from the purification unit for use as fuel.

3. A process according to claim 1, wherein the unsaturated compound is ethylene.

3 4 4. A process according to claim 1, wherein the unsatu- References Cited rated compound is acetylene. UNITED STATES PATENTS 5. A process according to claim 1, wherein both ethyl- 2,789,149 4/1957 Bogart et a1. 260 678 ene and acetylene are withdrawn from the punfication unit as products of the process. 5 FOREIGN PATENTS 6. A process according to claim 1, wherein the un- 926,896 5/ 1963 Great Britainvaporized portion of said crude oil is returned to said DELBERT E, GANTZ, Primary Examiner, pipe line downstream of the withdrawal point. Jr D. MYERS, Assistant Examiner. 

